Vintage AR-91 purchase

[Norman Nicolai]

I’ve been looking for years and I was finally able to locate a pair of AR’s with a 12” woofer for a reasonable price, a pair of AR-91’s. They’re not AR-3a’s, the holy grail, but it’s pretty close to that, so right now I’m pretty contented. I purchased them from a local seller in NJ who had them up on Craigslist. They seem to be in good cosmetic shap. They were re-foamed a few years ago, and sound terrific, although I’ve only listened to them a short while. I compared them to my stacked Advents, and while it’s hard to compete with the sheer “presence” of the Advent’s wall of sound, the 91’s sounded far more nuanced and accurate and they held their own. (However, stacked Advents still win in the bass department.)

At some point, I will open them up to check on the crossover capacitors, with an eye to replacing them. The binding posts will positively need to go. I use banana plugs for quick changing components in my basement lab/work room. The 91’s binding posts don’t fully accept a banana plug. They hang halfway out and the connection is not secure. I know this a matter of disagreement between some members on this site from reading past postings on AR-91’s. (…You’re a store of knowledge on everything AR and KLH, JKent, and I always read and respect your perspective, but on this particular issue I think you are mistaken.)

I’m driving them with my Mitsubishi DA-A10, using an Advent 300 as a preamp. The DA-A10 is conservatively rated at 100 wpc and is rated for 4 ohms. 

The cabinets look somewhat dry and will need a little work, along with the 3-way switches on the back looking tarnished and pitted, but overall they are in relatively good shape, and they sound terrific. I’m really happy to add a pair of 91’s to my 2ax’s, KLH, Advent, and EPI vintage speakers!

Here are some photos with the stacked Advents in the background:

[Aadams]

Congratulations! Nice find.  They were designed to be on the floor against a rear wall for optimal bass from room gain.  They should compete with the LAs in that position. Difference between a 3a and 91 is more emotional than aural. 

Regarding the Banana plugs:  I and others here have used 14 awg wire, ring connectors and female banana plugs screwed on the original binding posts to avoid altering the original correctly working speaker parts.  JIC you had not considered it.

[meta_noia_fot]

Nice find. I picked up a pair of 92's that I've been listening to for a few weeks. I recapped them using NPE's with film bypass caps. They sound really terrific.

[DavidR]

3 hours ago, meta_noia_fot said:

Nice find. I picked up a pair of 92's that I've been listening to for a few weeks. I recapped them using NPE's with film bypass caps. They sound really terrific.

I've found this is the best way to rebuild the xovers.

Been contemplating re-doing xovers in one of my pair of 9s over this way as my 10Pi and 90s sound 'right'.

[meta_noia_fot]

3 hours ago, DavidR said:

I've found this is the best way to rebuild the xovers.

Going back through my bookmarks, and it was your AR90 recapping thread that convinced me to give NPE's a try.

https://community.classicspeakerpages.net/topic/11173-re-cappi-my-ar90s/

 

[DavidR]

27 minutes ago, meta_noia_fot said:

Going back through my bookmarks, and it was your AR90 recapping thread that convinced me to give NPE's a try.

https://community.classicspeakerpages.net/topic/11173-re-cappi-my-ar90s/

 

Thanks. The crossover was designed for NPE so with no other changes to a film cap route they just don't sound 'right'.

I wouldn't use the Vishay 1837 again but only because they needed the leads lengthened and soldered quickly. The CD940C is better anyway.

 

[lARrybody]

Congratulations on your AR91 acquisition. Did you know that the grills for the AR92 and AR91 are interchangeable.  They also used the same boards, just slightly different capacitor and resister values.  I replaced the binding post with these inexpensive insulated post from parts express.

https://www.parts-express.com/Mini-Insulated-Binding-Post-2-Red-2-Black-320-3375?quantity=1

The banana plugs hang out about 3/16 in. ,but are very secure.   On more traditional AR speaker binding post I took Adamas approach with ring connecter adapters.

 

As far as recapping, the recommendation of using quality NPE's is spot on. I used all NPE's except for the 4uf which is a Dayton Precision Poly.  The Mundorf Plain and Janzen Smooth NPE's have been discontinued, but if you look around you can find other quality electrolytics. I also replaced the resisters with Mills resisters which have become very expensive nowadays. If you original sand cast resisters test fine, I would just reuse them. 

If your 91 boards have the Unicon capacitors you might want to keep them. Mine didn't. 

[DavidR]

43 minutes ago, lARrybody said:

Mundorf Plain and Janzen Smooth NPE's have been discontinued,

I know that F&T, a German capacitor company, made the Mundord Ecap and one of the Jantzen cap lines. Parts Connxton still have the Mundorf Plain.

https://www.partsconnexion.com/capacitors-ele-mundorf-e-cap-ac-series.html

https://www.partsconnexion.com/jantzen-elecap.html

Parts Express has NPEs made by Solen.   https://www.parts-express.com/electronic-parts/capacitors/non-polarized-electrolytic-capacitors

I'm not a big fan of MDL but they work.

[AR surround]

46 minutes ago, lARrybody said:

If your 91 boards have the Unicon capacitors you might want to keep them. Mine didn't. 

I second that.  I preemptively replaced the Unicon capacitors in a pair of Boston A70's with new NPE's.  It turned out to be dive into a rabbit hole that required adding resistance and F&F bypass caps to achieve acceptable sonic results.

[AR surround]

3 minutes ago, DavidR said:

Parts Express has NPEs made by Solen.

 

3 minutes ago, AR surround said:

I preemptively replaced the Unicon capacitors in a pair of Boston A70's with new NPE's.  It turned out to be dive into a rabbit hole that required adding resistance and F&F bypass caps to achieve acceptable sonic results.

Yeah, I replaced the Unicons with those Parts Express caps that DavidR references.   There's that "S-Word" yet again, David.  LOL

[Stimpy]

21 hours ago, lARrybody said:

If your 91 boards have the Unicon capacitors you might want to keep them. Mine didn't. 

I agree 100%.  The stock Unicon capacitors, in my AR58S speakers, still sounded great.  But, out of caution, I replaced them.  It took quite a bit of money, towards very decent poly caps, to improve upon the Unicon caps.  I wish those caps were still made, as they would be my go to NPE.

[RoyC]

4 hours ago, DavidR said:

I'm not a big fan of MDL but they work.

David,

I've actually been finding MDL caps to measure and perform as well as Parts Express npe caps. I use them interchangeably these days.

ERSE is the only common npe crossover cap I have found to be inferior, but I think that company went out of business.

Roy

[Stimpy]

26 minutes ago, RoyC said:

ERSE is the only common npe crossover cap I have found to be inferior, but I think that company went out of business.

Roy

From what I've read, the owner passed away, and the family didn't want to carry on with the business.  Now, it seems the Erse name is Chinese owned.  I'm not sure if that means parts from the old Erse facility, or from China?

Edit:  After a quick search, it seems the former Esre employees have started US Coils.  They look to provide many of the same components once supplied by Erse.  Good news, I hope?

US Coils

[lARrybody]

The company has been reborn.

https://www.audiosciencereview.com/forum/index.php?threads/erse-is-gone-us-coils-rises-like-a-phoenix-from-their-ashes.34999/

 

 

[Stimpy]

For what it's worth, M.D.L. looks to be it's own company; a Taiwanese manufacturer.

M.D.L.

Products

[RoyC]

19 hours ago, Stimpy said:

For what it's worth, M.D.L. looks to be it's own company; a Taiwanese manufacturer.

M.D.L.

Products

Some years ago I first found MDL capacitors as original equipment in speakers I was repairing for a local audio shop. Having been impressed with their measurements, I later purchased "buyout" MDL's from Parts Express with good luck. Since Madisound began carrying them, I've used quite a few for repairs and restorations of all types.

 

[JKent]

On 3/31/2023 at 3:46 PM, Stimpy said:

After a quick search, it seems the former Esre employees have started US Coils.  They look to provide many of the same components once supplied by Erse.  Good news, I hope?

US Coils

Good to know. I always found the  Erse film caps to be a good buy. Here's my 91 xo.

[JKent]

On 3/29/2023 at 12:02 AM, Norman Nicolai said:

 

The binding posts will positively need to go. I use banana plugs for quick changing components in my basement lab/work room. The 91’s binding posts don’t fully accept a banana plug. They hang halfway out and the connection is not secure. I know this a matter of disagreement between some members on this site from reading past postings on AR-91’s. (…You’re a store of knowledge on everything AR and KLH, JKent, and I always read and respect your perspective, but on this particular issue I think you are mistaken.)

 

Thanks for the kind words. I personally don't think it's a big deal. I use double bananas with the original binding posts and they work fine. But new 5-ways such as those Larry used certainly look nicer. Or you could go a little nuts and get some nice Cardas binding posts. No argument from me. And the 91s certainly deserve first class treatment IMHO.

Good luck with the resto.

[genek]

A portion of this discussion has been banished to The Kitchen. 

Disagree all you want about equipment and components, but not about each other's motives or behavior.